A rather weird study that looks at the impact of tooth loss on physical and cognitive health of older adults has popped up recently. This study is “weird” not necessarily because of its actual findings, but because of the way those findings are interpreted. While oral health may have correlations with various health problems and disabilities in old age, it probably isn’t the one that’s been concluded.

The research in question sought to assess correlations between tooth loss and “higher-level functional capacity” in older adults. This is a specific term that refers to the physical activities of daily living, intellectual activity, and ability to participate in social roles. The data all comes from Japan, though whether this means the findings are more or less applicable to an American audience is up for debate, especially given the logical missteps.

To summarize the findings: There was an association between tooth loss and declines in higher-level functional capacity over the two-year duration of the study. This was found to be dose-dependent, with more missing teeth being associated with stronger declines. Possible explanations for this association include inflammation (poor oral health means more oral inflammation), psychosocial influences (missing teeth has effects on facial expression and verbal communication), and nutrition (missing teeth indicates poor nutrition and limits chewing ability).

So far, these findings suggest a not-so-surprising correlation between oral health and physical and mental health, but things start to break down when getting to the researchers’ conclusion. They state that their models, “suggest that treatment for tooth loss attenuates [lessens] decline in higher-level functional capacity”.

To be blunt, this is a face-palming level of erroneous that shows a misunderstanding of correlation and causation, a basic element of cause-and-effect in research. Even if we assume the underlying suggestion (that missing teeth is correlated to higher-level functional decline) is correct, this says nothing about what sort of treatment might help. With the possible exception of social interactions and chewing, missing teeth would have minimal to no impact on existing declines in higher-level functional capacity. At best, it would result in a situation where you are treating a symptom or side-effect while neglecting the underlying problems responsible for the person’s current health state.

To be fair, it is possible that the researchers were referring to specific elements like social interaction or chewing when writing their conclusion. However, conclusions in research papers are usually very specific about what they are referring to and are normally able to be taken as they are written. The researchers wrote a broad statement, and so it will be judged as a broad statement.

Bottom line? Dental care is important and tooth loss may be one indicator that an older adult’s physical and cognitive health is in decline, but there are few logical reasons to think addressing tooth loss would improve any existing declines.